Curable composition and cured product thereof, method for producing cured product, method for manufacturing optical component, method for manufacturing circuit board, and method for manufacturing electronic component

ABSTRACT

To provide a curable composition for nanoimprinting that can form a cured product that has a sufficiently cured surface and is less prone to a pattern collapse defect even when the curable composition is cured by a photo-nanoimprint method at a low exposure dose. To provide a nanoimprint method for forming such a cured product. To provide a cured product that is less prone to a pattern collapse defect even when cured at a low exposure dose, a method for producing such a cured product, a method for manufacturing an optical component, a method for manufacturing a circuit board, and a method for manufacturing an electronic component. 
     A curable composition that satisfies the formula (1) in a cured state: 
         Er   1   /Er   2 ≧1.10  (1)
 
     wherein Er 1  denotes the surface reduced modulus (GPa) of a cured product of the curable composition, and Er 2  denotes the internal reduced modulus (GPa) of the cured product.

TECHNICAL FIELD

The present invention relates to a curable composition and a curedproduct thereof and to a method for producing a cured product.

BACKGROUND ART

There is a growing demand for fine semiconductor devices andmicroelectromechanical systems (MEMS). Thus, attention is being given tomicro- and nano-fabrication technology that utilizes as a mold a resist(photocurable composition) pattern having a predetermined shape formedon a substrate (wafer), as well as to known photolithography technology.This technology is also referred to as a photo-nanoimprint technique andcan be used to form a fine structure on the order of nanometers on asubstrate (see, for example, PTL 1). In the photo-nanoimprint technique,a resist is first placed in a patterning region on a substrate(placement step). The resist is then patterned with a patterned mold(mold contact step). The resist is then cured by photoirradiation(photoirradiation step) and is removed (demolding step). Through thesesteps, a resin pattern (photo-cured product) having a predeterminedshape is formed on the substrate. These steps can be performed multipletimes in other regions on the substrate to form fine structures over thesubstrate.

CITATION LIST Patent Literature

PTL 1: Japanese Patent Laid-Open No. 2010-073811

SUMMARY OF INVENTION Technical Problem

In the photoirradiation step of the photo-nanoimprint technique,however, a decreased exposure time, that is, a decreased exposure doseof the resist in order to improve throughput results in incompletecuring of the photocurable composition, causes a defect called patterncollapse in the demolding step, and unexpectedly results in a low yield.

When the curing is incomplete, pattern collapse tends to also occur inanother step after the demolding step. For example, in thephoto-nanoimprint technique, a series of steps (shot) from the placementstep to the demolding step are often performed multiple times on asingle substrate, and pattern collapse can occur during these steps.

The present invention provides a curable composition for nanoimprintingthat can form a cured product that has a sufficiently cured surface andis less prone to a pattern collapse defect even when the curablecomposition is cured by a photo-nanoimprint method at a low exposuredose. The present invention also provides a nanoimprint method forforming such a cured product. The present invention also provides acured product that is less prone to a pattern collapse defect even whencured at a low exposure dose, a method for producing such a curedproduct, a method for manufacturing an optical component, a method formanufacturing a circuit board, and a method for manufacturing anelectronic component.

The present invention provides a curable composition that satisfies thefollowing formula (1) in a cured state:

Er ₁ /Er≧1.10  (1)

wherein Er₁ denotes the surface reduced modulus (GPa) of a cured productof the curable composition, and Er₂ denotes the internal reduced modulus(GPa) of the cured product.

In accordance with the present invention, a curable composition thatsatisfies the formula (1) in a cured state can be used to form a curedproduct that is less prone to a pattern collapse defect even when thecurable composition is cured at a low exposure dose. The presentinvention can also provide a cured product that is less prone to apattern collapse defect even when cured at a low exposure dose, a methodfor producing such a cured product, a method for manufacturing anoptical component, a method for manufacturing a circuit board, and amethod for manufacturing an electronic component.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating a method formeasuring the surface reduced modulus and internal reduced modulus of acured product according to an embodiment of the present invention.

FIG. 2A is a schematic cross-sectional view illustrating a method forproducing a cured product according to an embodiment of the presentinvention.

FIG. 2B is a schematic cross-sectional view illustrating a method forproducing a cured product according to an embodiment of the presentinvention.

FIG. 2C is a schematic cross-sectional view illustrating a method forproducing a cured product according to an embodiment of the presentinvention.

FIG. 2D is a schematic cross-sectional view illustrating a method forproducing a cured product according to an embodiment of the presentinvention.

FIG. 2E is a schematic cross-sectional view illustrating a method forproducing a cured product according to an embodiment of the presentinvention.

FIG. 2F is a schematic cross-sectional view illustrating a method forproducing a cured product according to an embodiment of the presentinvention.

FIG. 2G is a schematic cross-sectional view illustrating a method forproducing a cured product according to an embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described in detail belowwith reference to the accompanying drawings.

Curable Composition

A curable composition according to the present embodiment satisfies thefollowing formula (1) in a cured state:

Er ₁ /Er ₂≧1.10  (1)

wherein Er₁ denotes the surface reduced modulus (GPa) of a cured productof the curable composition, and Er₂ denotes the internal reduced modulus(GPa) of the cured product.

A curable composition according to the present embodiment can berealized by appropriately choosing the type and concentration of eachcomponent of the composition. A curable composition according to thepresent embodiment can also be realized by choosing the composition suchthat a component of the curable composition has a concentrationdistribution.

A curable composition according to the present embodiment can containthe following components (A) and (B).

Component (A): Polymerizable compound

Component (B): Photopolymerization initiator

The term “cured product”, as used herein, refers to a product formed bycuring part or all of a curable composition by polymerization. A curedproduct having an excessively small thickness with respect to the areathereof is sometimes referred to as a cured film for emphasis.

A curable composition according to the present embodiment and a curedproduct thereof can have a particular pattern on a substrate.

The components will be described in detail below.

<Component (A): Polymerizable Compound>

The component (A) is a polymerizable compound. The term “polymerizablecompound”, as used herein, refers to a compound that reacts with apolymerizing factor (such as a radical) generated from aphotopolymerization initiator (component (B)) and forms a polymercompound film through a chain reaction (polymerization reaction).

For example, the polymerizable compound may be a radical polymerizablecompound. The polymerizable compound component (A) may be composed of apolymerizable compound or two or more polymerizable compounds.

The polymerizable compound component (A) can be all the polymerizablecompound component(s) of a curable composition according to the presentembodiment. In this case, the curable composition may be composed of apolymerizable compound alone or two or more particular polymerizablecompounds.

The radical polymerizable compound can be a compound having at least oneacryloyl or methacryloyl group, that is, a (meth)acrylic compound.

Thus, a curable composition according to the present embodiment cancontain a (meth)acrylic compound as the component (A). The component (A)can be composed mainly of a (meth)acrylic compound. All thepolymerizable compound component(s) of the curable composition can be a(meth)acrylic compound. The sentence “the component (A) is composedmainly of a (meth)acrylic compound”, as used herein, means that 90% byweight or more of the component (A) is the (meth)acrylic compound.

When the radical polymerizable compound is composed of two or morecompounds having at least one acryloyl or methacryloyl group, theradical polymerizable compound can contain a monofunctional acrylicmonomer and a polyfunctional acrylic monomer. This is because acombination of a monofunctional acrylic monomer and a polyfunctionalacrylic monomer can form a cured film having high mechanical strength.

Examples of a monofunctional (meth)acrylic compound having one acryloylor methacryloyl group include, but are not limited to, phenoxyethyl(meth)acrylate, phenoxy-2-methylethyl (meth)acrylate, phenoxyethoxyethyl(meth)acrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate,2-phenylphenoxyethyl (meth)acrylate, 4-phenylphenoxyethyl(meth)acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl (meth)acrylate,EO-modified p-cumylphenol (meth)acrylate, 2-bromophenoxyethyl(meth)acrylate, 2,4-dibromophenoxyethyl (meth)acrylate,2,4,6-tribromophenoxyethyl (meth)acrylate, EO-modified phenoxy(meth)acrylate, PO-modified phenoxy (meth)acrylate, polyoxyethylenenonylphenyl ether (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl(meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl(meth)acrylate, bornyl (meth)acrylate, tricyclodecanyl (meth)acrylate,dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate,cyclohexyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate,acryloylmorpholine, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl (meth)acrylate,ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate,butyl (meth)acrylate, amyl (meth)acrylate, isobutyl (meth)acrylate,t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate,hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate,isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl(meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl(meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl(meth)acrylate, isostearyl (meth)acrylate, benzyl (meth)acrylate,1-naphthylmethyl (meth)acrylate, 2-naphthylmethyl (meth)acrylate,tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate,ethoxydiethylene glycol (meth)acrylate, poly(ethylene glycol)mono(meth)acrylate, poly(propylene glycol) mono(meth)acrylate,methoxyethylene glycol (meth)acrylate, ethoxyethyl (meth)acrylate,methoxypoly(ethylene glycol) (meth)acrylate, methoxypoly(propyleneglycol) (meth)acrylate, diacetone (meth)acrylamide, isobutoxymethyl(meth)acrylamide, N,N-dimethyl (meth)acrylamide, t-octyl(meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl(meth)acrylate, 7-amino-3,7-dimethyloctyl (meth)acrylate, N,N-diethyl(meth)acrylamide, and N,N-dimethylaminopropyl (meth)acrylamide.

Examples of commercial products of a monofunctional (meth)acryliccompound include, but are not limited to, Aronix M101, M102, M110, M111,M113, M117, M5700, TO-1317, M120, M150, and M156 (manufactured byToagosei Co., Ltd.), MEDOL-10, MIBDOL-10, CHDOL-10, MMDOL-30, MEDOL-30,MIBDOL-30, CHDOL-30, LA, IBXA, 2-MTA, HPA, and Viscoat #150, #155, #158,#190, #192, #193, #220, #2000, #2100, and #2150 (manufactured by OsakaOrganic Chemical Industry Ltd.), Light Acrylate BO-A, EC-A, DMP-A,THF-A, HOP-A, HOA-MPE, HOA-MPL, PO-A, P-200A, NP-4EA, and NP-8EA, andEpoxy Ester M-600A (manufactured by Kyoeisha Chemical Co., Ltd.),Kayarad TC110S, R-564, and R-128H (manufactured by Nippon Kayaku Co.,Ltd.), NK ester AMP-10G and AMP-20G (manufactured by Shin NakamuraChemical Co., Ltd.), FA-511A, 512A, and 513A (manufactured by HitachiChemical Co., Ltd.), PHE, CEA, PHE-2, PHE-4, BR-31, BR-31M, and BR-32(manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), VP (manufactured byBASF), and ACMO, DMAA, and DMAPAA (manufactured by Kohjin Co., Ltd.).

Examples of a polyfunctional (meth)acrylic compound having two or moreacryloyl or methacryloyl groups include, but are not limited to,trimethylolpropane di(meth)acrylate, trimethylolpropanetri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate,PO-modified trimethylolpropane tri(meth)acrylate, EO,PO-modifiedtrimethylolpropane tri(meth)acrylate, dimethyloltricyclodecanedi(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethyleneglycol di(meth)acrylate, phenylethylene glycol di(meth)acrylate,poly(ethylene glycol) di(meth)acrylate, poly(propylene glycol)di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,9-nonanedioldi(meth)acrylate, 1,10-decanediol di(meth)acrylate,1,3-adamantanedimethanol di(meth)acrylate, o-xylylene di(meth)acrylate,m-xylylene di(meth)acrylate, p-xylylene di(meth)acrylate,tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tris(acryloyloxy)isocyanurate, bis(hydroxymethyl)tricyclodecane di(meth)acrylate,dipentaerythritol penta(meth)acrylate, dipentaerythritolhexa(meth)acrylate, EO-modified2,2-bis(4-((meth)acryloxy)phenyl)propane, PO-modified2,2-bis(4-((meth)acryloxy)phenyl)propane, and EO,PO-modified2,2-bis(4-((meth)acryloxy)phenyl)propane.

Examples of commercial products of a polyfunctional (meth)acryliccompound include, but are not limited to, Yupimer UV SA1002 and SA2007(manufactured by Mitsubishi Chemical Corp.), Viscoat #195, #230, #215,#260, #335HP, #295, #300. #360, #700, GPT, and 3PA (manufactured byOsaka Organic Chemical Industry Ltd.), Light Acrylate 4EG-A, 9EG-A,NP-A, DCP-A, BP-4EA, BP-4PA, TMP-A, PE-3A, PE-4A, and DPE-6A(manufactured by Kyoeisha Chemical Co., Ltd.), Kayarad PET30, TMPTA,R-604, DPHA, DPCA-20, -30, -60, and -120, HX-620, D-310, and D-330(manufactured by Nippon Kayaku Co., Ltd.), Aronix M208, M210, M215,M220, M240, M305, M309, M310, M315, M325, and M400 (manufactured byToagosei Co., Ltd.), and Ripoxy VR-77, VR-60, and VR-90 (manufactured byShowa Denko K.K.).

The term “(meth)acrylate” in these compounds refers to an acrylate or amethacrylate having the same alcohol residue as its correspondingacrylate. The term “(meth)acryloyl group” refers to an acryloyl group ora methacryloyl group having the same alcohol residue as itscorresponding acryloyl group. EO refers to ethylene oxide. AnEO-modified compound A refers to a compound in which a (meth)acrylicacid residue and an alcohol residue of the compound A are bound togetherthrough an ethylene oxide group block structure. PO refers to propyleneoxide. A PO-modified compound B refers to a compound in which a(meth)acrylic acid residue and an alcohol residue of the compound B arebound together through a propylene oxide group block structure.

Among these, the component (A) may contain at least one or at least twoof isobornyl acrylate, benzyl acrylate, 2-naphthylmethyl acrylate,dicyclopentanyl acrylate, m-xylylene diacrylate,dimethyloltricyclodecane diacrylate, phenylethylene glycol diacrylate,1,10-decanediol diacrylate, and neopentyl glycol diacrylate. Thecomponent (A) can be composed of isobornyl acrylate, benzyl acrylate,and neopentyl glycol diacrylate, or benzyl acrylate and m-xylylenediacrylate, or benzyl acrylate, 2-naphthylmethyl acrylate, andm-xylylene diacrylate, or benzyl acrylate and dimethyloltricyclodecanediacrylate, or benzyl acrylate and phenylethylene glycol diacrylate, ordicyclopentanyl acrylate and m-xylylene diacrylate, or isobornylacrylate and 1,10-decanediol diacrylate.

The component (A) can be composed mainly of a (meth)acrylic compound,and 20% by weight or more of the component (A) can be a polyfunctional(meth)acrylic compound. In this case, the resulting cured product canhave not only high mechanical strength due to cross-linking but also lowcure shrinkage and high pattern accuracy.

The component (A) can be composed mainly of a (meth)acrylic compound,and 30% by weight or more of the component (A) can be a (meth)acryliccompound having a ring structure. In this case, the resulting curedproduct can have higher mechanical strength.

The component (A) can be composed mainly of dicyclopentanyl acrylate andm-xylylene diacrylate, and the weight ratio of dicyclopentanyl acrylateto m-xylylene diacrylate can range from 40:60 to 60:40. The resultingcured product can have a good balance between various properties, suchas mechanical strength, curing rate, cure shrinkage, dry etchresistance, heat resistance, and PFP process compatibility.

<Component (B): Photopolymerization Initiator>

The component (B) is a photopolymerization initiator.

In the present embodiment, a photopolymerization initiator is a compoundthat senses light having a predetermined wavelength and generates apolymerizing factor (radical). More specifically, a photopolymerizationinitiator is a polymerization initiator (radical generator) that cangenerate a radical when induced by light (for example, infrared light,visible light, ultraviolet light, far-ultraviolet light, X-rays, chargedparticle beams, such as an electron beam, or radiation).

The component (B) may be composed of a photopolymerization initiator ortwo or more photopolymerization initiators.

Examples of the radical generator include, but are not limited to,optionally substituted 2,4,5-triarylimidazole dimers, such as a2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, a2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer, a2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, and a 2-(o- orp-methoxyphenyl)-4,5-diphenylimidazole dimer; benzophenone derivatives,such as benzophenone, N,N′-tetramethyl-4,4′-diaminobenzophenone(Michler's ketone), N,N′-tetraethyl-4,4′-diaminobenzophenone,4-methoxy-4′-dimethylaminobenzophenone, 4-chlorobenzophenone,4,4′-dimethoxybenzophenone, and 4,4′-diaminobenzophenone; α-aminoaromatic ketone derivatives, such as2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one; quinones, such as2-ethylanthraquinone, phenanthrenequinone, 2-t-butylanthraquinone,octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone,2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone,2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone,2-methyl-1,4-naphthoquinone, and 2,3-dimethylanthraquinone: benzoinether derivatives, such as benzoin methyl ether, benzoin ethyl ether,and benzoin phenyl ether; benzoin derivatives, such as benzoin,methylbenzoin, ethylbenzoin, and propylbenzoin; benzyl derivatives, suchas benzyl dimethyl ketal; acridine derivatives, such as 9-phenylacridineand 1,7-bis(9,9′-acridinyl)heptane; N-phenylglycine derivatives, such asN-phenylglycine; acetophenone derivatives, such as acetophenone,3-methylacetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexylphenyl ketone, and 2,2-dimethoxy-2-phenylacetophenone; thioxanthonederivatives, such as thioxanthone, diethylthioxanthone,2-isopropylthioxanthone, and 2-chlorothioxanthone; acylphosphine oxidederivatives, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide,bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, andbis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; oximeester derivatives, such as1,2-octanedione,1-[4-(phenylthio)-,2-(O-benzoyloxime)] andethanone,1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-,1-(O-acetyloxime);xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone,triphenylamine, carbazole,1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, and2-hydroxy-2-methyl-1-phenylpropan-1-one.

Examples of commercial products of the radical generator include, butare not limited to, Irgacure 184, 369, 651, 500, 819, 907, 784, 2959,CGI-1700, -1750, and -1850, CG24-61, Darocur 1116 and 1173, Lucirin TPO,LR8893, and LR8970 (manufactured by BASF), and Uvecryl P36 (manufacturedby Sigma-Aldrich GmbH).

Among these, the component (B) of a curable composition according to thepresent embodiment may contain at least one of alkylphenonepolymerization initiators and acylphosphine oxide polymerizationinitiators.

Among the examples, alkylphenone polymerization initiators are benzoinether derivatives, such as benzoin methyl ether, benzoin ethyl ether,and benzoin phenyl ether, benzoin derivatives, such as benzoin,methylbenzoin, ethylbenzoin, and propylbenzoin; benzyl derivatives, suchas benzyl dimethyl ketal; acetophenone derivatives, such asacetophenone, 3-methylacetophenone, acetophenone benzyl ketal,1-hydroxycyclohexyl phenyl ketone, and2,2-dimethoxy-2-phenylacetophenone: and α-amino aromatic ketonederivatives, such as2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 and2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one.

Among the examples, acylphosphine oxide polymerization initiators areacylphosphine oxide compounds, such as2,4,6-trimethylbenzoyldiphenylphosphine oxide,bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, andbis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

Among these, the component (B) may be benzyl dimethyl ketal representedby the following formula (a),2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 representedby the following formula (b), or 2,4,6-trimethylbenzoyldiphenylphosphineoxide represented by the following formula (f).

The percentage of the photopolymerization initiator component (B) in acurable composition according to the present embodiment is 0.01% byweight or more and 10% by weight or less, preferably 0.1% by weight ormore and 7% by weight or less, of the total amount of the polymerizablecompound component (A).

When the percentage of the component (B) is 0.01% by weight or more ofthe total amount of the polymerizable compound, a curable compositionaccording to the present embodiment can have a high curing rate and highreaction efficiency. When the percentage of the component (B) is 10% byweight or less of the total amount of the polymerizable compound, theresulting cured product has certain mechanical strength.

The component (B) can contain at least one of2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 and2,4,6-trimethylbenzoyldiphenylphosphine oxide. In this case, a curablecomposition for nanoimprinting according to the present embodiment canform a cured product that has a sufficiently cured surface and is lessprone to a pattern collapse defect without an additive component (C).

The component (A) can be composed mainly of dicyclopentanyl acrylate andm-xylylene diacrylate, the weight ratio of dicyclopentanyl acrylate tom-xylylene diacrylate ranges from 40:60 to 60:40, and the amount ofcomponent (B) ranges from 0.01% to 10% by weight of the total amount ofthe component (A). The resulting cured product can have a good balancebetween various properties, such as mechanical strength, curing rate,cure shrinkage, dry etch resistance, heat resistance, and PFP processcompatibility.

<Another Additive Component (C)>

In addition to the component (A) and the component (B), a curablecomposition according to the present embodiment may contain an additivecomponent (C) depending on the purpose without losing the advantages ofthe present invention. Examples of the additive component (C) include,but are not limited to, a sensitizer, a hydrogen donor, an internalrelease agent, a surfactant, an antioxidant, a solvent, a polymercomponent, and a polymerization initiator other than the component (B).

A sensitizer is a compound appropriately added to promote apolymerization reaction and improve the reaction conversion. Asensitizer may be a sensitizing dye.

A sensitizing dye is a compound that is excited by absorbing lighthaving a particular wavelength and interacts with thephotopolymerization initiator component (B). The interaction may beenergy transfer or electron transfer from an excited sensitizing dye tothe photopolymerization initiator component (B).

Specific examples of the sensitizing dye include, but are not limitedto, anthracene derivatives, anthraquinone derivatives, pyrenederivatives, perylene derivatives, carbazole derivatives, benzophenonederivatives, thioxanthone derivatives, xanthone derivatives, coumarinderivatives, phenothiazine derivatives, camphorquinone derivatives,acridine dyes, thiopyrylium salt dyes, merocyanine dyes, quinoline dyes,styrylquinoline dyes, ketocoumarin dyes, thioxanthene dyes, xanthenedyes, oxonol dyes, cyanine dyes, rhodamine dyes, and pyrylium salt dyes.

These sensitizers may be used alone or in combination of two or morethereof.

Among these, the sensitizer may be a sensitizer having a benzophenonestructure.

The sensitizer having a benzophenone structure is a benzophenonecompound, such as a 4,4′-bis(dialkylamino)benzophenone.

Among these, the sensitizer may be 4,4′-bis(diethylamino)benzophenonerepresented by the following formula (g).

At least one sensitizer having a benzophenone structure can be added asa sensitizer. A sensitizer having a benzophenone structure can improvethe curing rate without decreasing mechanical strength.

A hydrogen donor is a compound that reacts with an initiator radicalgenerated from the photopolymerization initiator component (B) or aradical at the polymerization growth terminal to form a more reactiveradical. A hydrogen donor can be added when the photopolymerizationinitiator component (B) is a photo radical generator.

Specific examples of the hydrogen donor include, but are not limited to,amine compounds, such as n-butylamine, di-n-butylamine,tri-n-butylphosphine, allylthiourea, s-benzylisothiuronium-p-toluenesulfinate, triethylamine, diethylaminoethyl methacrylate,triethylenetetramine, 4,4′-bis(dialkylamino)benzophenones, ethylN,N-dimethylaminobenzoate, isoamyl N,N-dimethylaminobenzoate,pentyl-4-dimethylaminobenzoate, triethanolamine, and N-phenylglycine;and mercapto compounds, such as 2-mercapto-N-phenylbenzimidazole andmercaptopropionic acid esters.

These hydrogen donors may be used alone or in combination of two or morethereof.

The hydrogen donor may have a function of a sensitizer. A hydrogen donorhaving a function of a sensitizer may be a4,4′-bis(dialkylamino)benzophenone.

4,4′-bis(dialkylamino)benzophenones include4,4′-bis(diethylamino)benzophenone and derivatives thereof. Among these,4,4′-bis(diethylamino)benzophenone represented by the following formula(f) may be used.

At least one hydrogen donor having a benzophenone structure can be addedas a hydrogen donor. A hydrogen donor having a benzophenone structurecan improve the curing rate without decreasing mechanical strength.

When a curable composition according to the present embodiment containsa sensitizer and/or a hydrogen donor as an additive component (C), theamount of each additive component (C) is preferably 0% by weight or moreand 20% by weight or less, more preferably 0.1% by weight or more and5.0% by weight or less, still more preferably 0.2% by weight or more and2.0% by weight or less, of the total amount of the polymerizablecompound component (A). When the sensitizer content is 0.1% by weight ormore of the total amount of the component (A), the polymerizationpromoting effect becomes more effective. When the sensitizer or hydrogendonor content is 5.0% by weight or less, a polymer compound constitutingthe resulting photo-cured product can have a sufficiently high molecularweight, and poor dissolution of the sensitizer or hydrogen donor in thecurable composition and deterioration of storage stability of thecurable composition can be suppressed.

An internal release agent can be added to a curable compositionaccording to the present embodiment in order to decrease the interfacialbond strength between a mold and a resist, that is, the demolding forcein the demolding step. The term “internal”, as used herein in thecontext of an additive, means that the additive is added in advance to acurable composition before the placement step.

The internal release agent may be a surfactant, such as a siliconesurfactant, a fluorosurfactant, or a hydrocarbon surfactant. In thepresent embodiment, the internal release agent has no polymerizationreactivity.

Examples of the fluorosurfactant include, but are not limited to,poly(alkylene oxide) (such as poly(ethylene oxide) or poly(propyleneoxide)) adducts of alcohols having a perfluoroalkyl group andpoly(alkylene oxide) (such as poly(ethylene oxide) or poly(propyleneoxide)) adducts of perfluoropolyethers. The fluorosurfactant may have ahydroxyl group, an alkoxy group, an alkyl group, an amino group, and/ora thiol group as part of its molecular structure (for example, as an endgroup).

The fluorosurfactant may be a commercial product. Examples of thecommercial product include, but are not limited to, Megaface F-444,TF-2066, TF-2067, and TF-2068 (manufactured by DIC Corporation), FluoradFC-430 and FC-431 (manufactured by Sumitomo 3M Ltd.), Surflon S-382(manufactured by AGC Seimi Chemical Co., Ltd.), EFTOP EF-122A, 122B,122C, EF-121, EF-126, EF-127, and MF-100 (manufactured by TohkemProducts Corporation), PF-636, PF-6320, PF-656, and PF6520 (manufacturedby OMNOVA Solutions Inc.), Unidyne DS-401, DS-403, and DS451(manufactured by Daikin Industries, Ltd.), and Ftergent 250, 251, 222F,and 208G (manufactured by NEOS Co. Ltd.).

Among these fluorosurfactants, the internal release agent may be apoly(alkylene oxide) adduct of an alcohol having a perfluoroalkyl group.The internal release agent may be a compound represented by thefollowing formula (c).

The internal release agent may be a hydrocarbon surfactant.

The hydrocarbon surfactant may be an alkyl alcohol poly(alkylene oxide)adduct in which an alkylene oxide having 2 to 4 carbon atoms is added toan alkyl alcohol having 1 to 50 carbon atoms.

Examples of the alkyl alcohol poly(alkylene oxide) adduct include, butare not limited to, methyl alcohol ethylene oxide adducts, decyl alcoholethylene oxide adducts, lauryl alcohol ethylene oxide adducts, cetylalcohol ethylene oxide adducts, stearyl alcohol ethylene oxide adducts,and stearyl alcohol ethylene oxide/propylene oxide adducts. An end groupof the alkyl alcohol poly(alkylene oxide) adduct is not limited to ahydroxyl group resulting from simple addition of poly(alkylene oxide) toan alkyl alcohol. This hydroxyl group may be substituted by anothersubstituent, for example, a polar functional group, such as a carboxylgroup, an amino group, a pyridyl group, a thiol group, or a silanolgroup, or a hydrophobic functional group, such as an alkyl group or analkoxy group.

The alkyl alcohol poly(alkylene oxide) adduct may be a commercialproduct. Examples of the commercial product include, but are not limitedto, polyoxyethylene methyl ethers (methyl alcohol ethylene oxideadducts) manufactured by Aoki Oil Industrial Co., Ltd. (BLAUNON MP-400,MP-550, and MP-1000), polyoxyethylene decyl ethers (decyl alcoholethylene oxide adducts) manufactured by Aoki Oil Industrial Co., Ltd.(FINESURF D-1303, D-1305, D-1307, and D-1310), a polyoxyethylene laurylether (lauryl alcohol ethylene oxide adducts) manufactured by Aoki OilIndustrial Co., Ltd. (BLAUNON EL-1505), polyoxyethylene cetyl ethers(cetyl alcohol ethylene oxide adducts) manufactured by Aoki OilIndustrial Co., Ltd. (BLAUNON CH-305 and CH-310), polyoxyethylenestearyl ethers (stearyl alcohol ethylene oxide adducts) manufactured byAoki Oil Industrial Co., Ltd. (BLAUNON SR-705, SR-707, SR-715, SR-720,SR-730, and SR-750), random polymerization type polyoxyethylenepolyoxypropylene stearyl ethers manufactured by Aoki Oil Industrial Co.,Ltd. (BLAUNON SA-50/50 1000R and SA-30/70 2000R), a polyoxyethylenemethyl ether manufactured by BASF (Pluriol A760E), and polyoxyethylenealkyl ethers manufactured by Kao Corporation (Emulgen series).

Among these hydrocarbon surfactants, the internal release agent may bean alkyl alcohol poly(alkylene oxide) adduct or a long-chain alkylalcohol poly(alkylene oxide) adduct. The internal release agent may be acompound represented by the following formula (d), (h), or (i).

The internal release agents may be used alone or in combination of twoor more thereof.

When a curable composition according to the present embodiment containsan internal release agent, the internal release agent can be at leastone of fluorosurfactants and hydrocarbon surfactants.

When a curable composition according to the present embodiment containsan internal release agent as an additive component (C), the internalrelease agent content may be 0.001% by weight or more and 10% by weightor less, preferably 0.01% by weight or more and 7% by weight or less,more preferably 0.05% by weight or more and 5% by weight or less, of thetotal amount of the polymerizable compound component (A).

When the internal release agent content is 0.001% by weight or more and10% by weight or less, the curable composition can form a cured productthat has a sufficiently cured surface and is less prone to a patterncollapse defect even when the curable composition is cured at a lowexposure dose. This also improves the effect of decreasing demoldingforce and/or improves the filling property.

A curable composition according to the present embodiment can be acomposition for photo-nanoimprinting.

The percentages of the component (A) and the component (B) can bedetermined by infrared spectroscopy, ultraviolet-visible spectroscopy,or pyrolysis gas chromatography-mass spectrometry of a curablecomposition according to the present embodiment and/or a cured productthereof. As a result, the percentages of the component (A) and thecomponent (B) in the curable composition can be determined. When acurable composition according to the present embodiment contains anadditive component (C), the percentages of the component (A), thecomponent (B), and the additive component (C) in the curable compositioncan be determined in the same manner.

<Temperature of Curable Composition in Blending>

In the preparation of a curable composition according to the presentembodiment, at least the component (A) and the component (B) are mixedand dissolved under predetermined temperature conditions. Morespecifically, the temperature is 0° C. or more and 100° C. or less. Theadditive component (C) is also mixed and dissolved in the same manner.

<Viscosity of Curable Composition>

A mixture of the components of a curable composition according to thepresent embodiment other than the solvent thereof preferably has aviscosity of 1 cP or more and 100 cP or less, more preferably 1 cP ormore and 50 cP or less, still more preferably 1 cP or more and 20 cP orless, at 23° C.

A curable composition having a viscosity of 100 cP or less can fill intoa recessed portion of a micro- and/or nano-pattern on a mold in a shorttime when the mold pattern comes into contact with the curablecomposition. The cured product is less prone to a pattern defect due toincomplete filling.

A curable composition having a viscosity of 1 cP or more can beuniformly applied to a substrate and can make less flow out of a moldedge.

<Surface Tension of Curable Composition>

A mixture of the components of a curable composition according to thepresent embodiment other than the solvent thereof preferably has asurface tension of 5 mN/m or more and 70 mN/m or less, more preferably 7mN/m or more and 35 mN/m or less, still more preferably 10 mN/m or moreand 32 mN/m or less, at 23° C. A curable composition having a surfacetension of 5 mN/m or more can flow into a recessed portion of a micro-and/or nano-pattern on a mold in a short time.

A cured product of a curable composition having a surface tension of 70mN/m or less has a smooth surface.

<Impurities in Curable Composition>

A curable composition according to the present embodiment contains asfew impurities as possible. The impurities refer to components otherthan the component (A), the component (B), and the additive component(C).

Thus, a curable composition according to the present embodiment can besubjected to a purification step. The purification step can befiltration through a filter.

For filtration through a filter, a mixture of the component (A), thecomponent (B), and the optional additive component (C) can be passedthrough a filter, for example, having a pore size of 0.001 μm or moreand 5.0 μm or less. For filtration through a filter, the filtration canbe performed in multiple stages or multiple times. A filtered liquid maybe filtered again. A plurality of filters having different pore sizesmay be used. A filter for filtration may be, but is not limited to, apolyethylene filter, a polypropylene filter, a fluoropolymer filter, ora nylon filter.

Impurities, such as particles, in a curable composition according to thepresent embodiment can be removed in the purification step. This canprevent impurities, such as particles, from accidentally formingasperities to cause a pattern defect on a cured product of the curablecomposition.

When a curable composition according to the present embodiment is usedfor the manufacture of semiconductor integrated circuits, it isdesirable to avoid contamination of the curable composition withimpurities containing metal atoms (metal impurities) so as not to affectthe operation of the product. To this end, the concentration of metalimpurities in a curable composition according to the present embodimentis preferably 10 ppm or less, more preferably 100 ppb or less.

Cured Product

A cured product can be prepared by curing a curable compositionaccording to the present embodiment. In this case, a coating film of thecurable composition can be cured. A specific example of a method forforming a coating film of a curable composition is described in aplacement step [1] of a method for producing a patterned cured productdescribed below. A specific example of a method for curing a coatingfilm is described in a method for irradiating a curable composition withlight in a photoirradiation step [4] in a method for producing apatterned cured product.

<Measurement of Reduced Modulus of Cured Product>

The reduced modulus of a cured product can be measured bynanoindentation. In nanoindentation, an indenter is forced into adesired portion of a sample, and the load and displacement aresimultaneously measured. The hardness and reduced modulus of the samplecan be determined from the relationship between the load anddisplacement. When the reduced modulus of a cured product on a substrateis measured as in the present embodiment, the indentation depth isdetermined such that the substrate does not affect the measurement.

The specific measuring apparatus may be Nano Indenter G200 (manufacturedby Agilent Technologies), ENT series (manufactured by Elionix Inc.), orTI series (manufactured by Hysitron Corporation). Particularly in thepresent invention, it is desirable to use a measuring apparatus that cancontrol and measure a small displacement and a small load required formeasurement in a very thin surface layer (a depth of less than 10 nmfrom a surface) of a cured product.

A curable composition according to the present embodiment satisfies thefollowing formula (1) in a cured state, wherein Er₁ denotes the surfacereduced modulus (GPa) of a cured product of the curable composition, andEr₂ denotes the internal reduced modulus (GPa) of the cured product.

Er ₁ /Er ₂≧1.10  (1)

The surface reduced modulus Er₁ (GPa) of a cured product can be measuredas an average reduced modulus in a depth range of 4 nm or less from asurface of the cured product by determining the relationship betweenload (P) and displacement (indentation depth h) while the surface isindented with an indenter to an indentation depth of approximately 10 nmwith a TI-950 TriboIndenter (manufactured by Hysitron Corporation),determining the slope P^(2/3)/h in a region in which a “P^(2/3) vs. h”line is substantially straight (immediately after loading, at anindentation depth in the range of 0 to 4 nm) by the Hertz method, andsubstituting the slope P^(2/3)/h into the following mathematical formula(1).

In the mathematical formula (1), R denotes the tip radius of theindenter used for the measurement. The indenter tip radius R can bedetermined using this formula from nanoindentation of a standard samplehaving a known modulus.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 1} \right\rbrack & \; \\{{Er}_{1} = {\frac{3}{4}\left( {\frac{1}{R^{1/2}}\frac{P}{h^{3/2}}} \right)}} & {{Formula}\mspace{14mu} (1)}\end{matrix}$

The internal reduced modulus Er₂ (GPa) of the cured product can bemeasured at a depth of 200 nm from a surface of the cured product bydetermining the relationship between load (P) and displacement(indentation depth h) while the surface of the cured product is indentedwith an indenter to an indentation depth of 200 nm with a TI-950Triboindenter (manufactured by Hysitron Corporation) and substitutingthe slope S of a tangent line of the “P vs. h” curve immediately afterunloading into the following mathematical formula (2) by theOliver-Pharr method. In the mathematical formula (2). A_(c) denotes thecontact projected area, which depends on the indenter used for themeasurement and the indentation depth. The contact projected area A canbe determined from a calibration curve (the relationship between theindentation depth and the contact projected area of the indenter)obtained using this formula from nanoindentation of a standard samplehaving a known modulus.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 2} \right\rbrack & \; \\{{Er}_{2} = \frac{S\sqrt{\pi}}{2\sqrt{A_{c}}}} & {{Formula}\mspace{14mu} (2)}\end{matrix}$

The thickness of a cured product subjected to the measurement of areduced modulus can be 2.0 μm or more. The reduced modulus of a curedproduct can be measured, for example, 24 hours after a curablecomposition is cured.

FIG. 1 is a schematic cross-sectional view illustrating a method formeasuring the surface reduced modulus and internal reduced modulus of acured product according to the present embodiment.

A curable composition that satisfies the formula (1) can form a curedproduct that has a sufficiently cured surface and is less prone to apattern collapse defect even when the curable composition is cured at alow exposure dose.

The curable composition can also satisfy the formula (2) in a curedstate.

Er ₁ /Er ₂≧1.40  (2)

Er₁ and Er₂ in the formula (2) are the same as Er₁ and Er₂ in theformula (1). Thus. Er₁ can be measured as an average reduced modulus(GPa) in a depth range of 4 nm or less from a surface of the curedproduct, and Er₂ can be measured as a reduced modulus (GPa) at a depthof 200 nm from the surface of the cured product.

The curable composition can also satisfy the following formula (3) aswell as the formula (1) or (2) in a cured state.

Er ₁≧3.00 GPa  (3)

The curable composition can also satisfy the formula (4) in a curedstate.

Er ₁>3.50 GPa  (4)

Er₁ in the formulae (3) and (4) is the same as Er₁ in the formula (1) or(2) and denotes an average reduced modulus (GPa) in a depth range of 4nm or less from the surface of the cured product.

Method for Producing Patterned Cured Product

A method for producing a patterned cured product according to thepresent embodiment will be described below.

FIGS. 2A to 2G are schematic cross-sectional views illustrating anexample of a method for producing a patterned cured product according tothe present embodiment.

A method for producing a patterned cured product according to thepresent embodiment includes

-   -   [1] a placement step of placing a curable composition according        to the present embodiment on a substrate,    -   [2] a mold contact step of bringing the curable composition into        contact with a mold,    -   [3] an aligning step of aligning the substrate with the mold,    -   [4] a photoirradiation step of irradiating the curable        composition with light, and    -   [5] a demolding step of separating a cured product formed in the        step [4] from the mold.

A method for producing a patterned cured product according to thepresent embodiment is a method for producing a film by aphoto-nanoimprint method.

A cured product produced by a method for producing a patterned curedproduct according to the present embodiment is preferably a film havinga pattern having a size of 1 nm or more and 10 mm or less, morepreferably a film having a pattern having a size of 10 nm or more and100 μm or less. In general, a patterning technique for forming a filmhaving a nanoscale (1 nm or more and 100 nm or less) pattern (texturedstructure) utilizing light is referred to as a photo-nanoimprint method.A method for producing a patterned cured product according to thepresent embodiment utilizes the photo-nanoimprint method.

Each of the steps will be described below.

<Placement Step [1]>

In this step (placement step), as illustrated in FIG. 2A, a curablecomposition 101 according to the present embodiment is placed on(applied to) a substrate 102 to form a coating film.

The substrate 102 on which the curable composition 101 is to be placedis a workpiece substrate and is generally a silicon wafer.

In the present embodiment, the substrate 102 is not limited to a siliconwafer and may be a known substrate for use in semiconductor devices,such as an aluminum, titanium-tungsten alloy, aluminum-silicon alloy,aluminum-copper-silicon alloy, silicon oxide, or silicon nitridesubstrate. The substrate 102 (workpiece substrate) may be a substratethat is subjected to surface treatment, such as silane couplingtreatment, silazane treatment, or formation of an organic thin film, toimprove adhesion to a curable composition.

In the present embodiment, a curable composition can be placed on theworkpiece substrate by an ink jet method, a dip coating method, an airknife coating method, a curtain coating method, a wire bar coatingmethod, a gravure coating method, an extrusion coating method, a spincoating method, or a slit scanning method. An ink jet method may be usedfor the photo-nanoimprint method. The thickness of a layer to which apattern is to be transferred (a coating film) depends on the applicationand may be 0.01 μm or more and 100.0 μm or less.

<Mold Contact Step [2]>

As illustrated in FIG. 2B, the curable composition 101 is then broughtinto contact with a mold 104 having an original pattern that is to betransferred to the coating film of the curable composition 101 formed inthe previous step (placement step). When the curable composition 101 (alayer to which a pattern is to be transferred) is brought into contactwith the mold 104 in the present step (FIG. 2B(b-1)), recessed portionsof a micro- and/or nano-pattern on a surface of the mold 104 are filledwith (part of) the coating film of the curable composition 101, thusforming a coating film 106 in the micro- and/or nano-pattern on the mold104 (FIG. 2B(b-2)).

Considering the next step (photoirradiation step), the mold 104 is madeof a light-transmitting material. More specifically, the mold 104 can bemade of glass, quartz, a transparent resin, such as PMMA orpolycarbonate, a transparent metal deposited film, a flexible film, suchas a polydimethylsiloxane film, a photo-cured film, or a metal film.When the mold 104 is made of a transparent resin, the transparent resinshould not be dissolved in the components of the curable composition101. Quartz is preferable for the mold 104 because of a low thermalexpansion coefficient and low pattern distortion.

The micro- and nano-pattern on the surface of the mold 104 can have apattern height of 4 nm or more and 200 nm or less and an aspect ratio of1 or more and 10 or less.

In order to improve the detachability of the curable composition 101from the surface of the mold 104, the mold 104 may be subjected tosurface treatment before the present step of bringing the curablecomposition into contact with the mold. The surface treatment may beperformed by applying a release agent to the surface of the mold to forma release agent layer. The release agent to be applied to the surface ofthe mold may be a silicone release agent, a fluorinated release agent, ahydrocarbon release agent, a polyethylene release agent, a polypropylenerelease agent, a paraffinic release agent, a montan release agent, or acarnauba release agent. For example, a commercially available coatingtype release agent, such as Optool DSX manufactured by DaikinIndustries, Ltd., may be used. These release agents may be used alone orin combination of two or more thereof. Among these, a fluorinatedrelease agent and/or a hydrocarbon release agent may be used.

In the present step (mold contact step), as illustrated in FIG. 2B(b-1),when the mold 104 is brought into contact with the curable composition101, the pressure applied to the curable composition 101 is notparticularly limited and is generally 0 MPa or more and 100 MPa or less,preferably 0 MPa or more and 50 MPa or less, more preferably 0 MPa ormore and 30 MPa or less, still more preferably 0 MPa or more and 20 MPaor less.

In the present step, the contact time between the mold 104 and thecurable composition 101 is not particularly limited and is generally 0.1seconds or more and 600 seconds or less, preferably 0.1 seconds or moreand 300 seconds or less, more preferably 0.1 seconds or more and 180seconds or less, still more preferably 0.1 seconds or more and 120seconds or less.

The present step may be performed in the ambient atmosphere, underreduced pressure, or in an inert gas atmosphere. The effects of oxygenand moisture on the curing reaction can be suppressed under reducedpressure or in an inert gas atmosphere. When the present step isperformed in an inert gas atmosphere, the inert gas may be nitrogen,carbon dioxide, helium, argon, a flon, the alternative thereof, or amixture thereof. When the present step is performed in the ambientatmosphere or in a particular gas atmosphere, the pressure is 0.0001 atmor more and 10 atm or less.

The mold contact step may be performed in an atmosphere containing acondensable gas (hereinafter referred to as a condensable gasatmosphere). The term “condensable gas”, as used herein, refers to a gasthat is in gaseous form in the atmosphere before the contact between thecurable composition 101 (a layer to which a pattern is to betransferred) and the mold 104 in the mold contact step (FIG. 2B(b-1))and is condensed and liquefied under capillary pressure resulting fromfilling pressure when the recessed portions of the micro- and/ornano-pattern on the mold 104 and a gap between the mold 104 and thesubstrate 102 are filled with the gas in the atmosphere together with(part of) the coating film 106 upon contact between the curablecomposition 101 (a layer to which a pattern is to be transferred) andthe mold 104.

In the mold contact step in a condensable gas atmosphere, the gas in therecessed portions of the micro- and/or nano-pattern is liquefied, andgas bubbles disappear, which improves the filling property. Thecondensable gas may be dissolved in the curable composition.

The boiling point of the condensable gas is below the ambienttemperature of the mold contact step and preferably ranges from −10° C.to 23° C. more preferably 10° C. to 23° C. A boiling point in this rangeresults in further improved filling property.

The vapor pressure of the condensable gas at the ambient temperature inthe mold contact step is below the mold pressure applied in the moldcontact step and preferably ranges from 0.1 to 0.4 MPa. A vapor pressurein this range results in further improved filling property. A vaporpressure of more than 0.4 MPa at the ambient temperature tends to resultin insufficient effects of disappeared gas bubbles. On the other hand, avapor pressure of less than 0.1 MPa at the ambient temperature requiredpressure reduction, which tends to make the apparatus complex.

The ambient temperature in the mold contact step is not particularlylimited and preferably ranges from 20° C. to 25° C.

The condensable gas may be a flon or the alternative thereof, forexample, chlorofluorocarbon (CFC), such as trichlorofluoromethane,fluorocarbon (FC), hydrochlorofluorocarbon (HCFC), hydrofluorocarbon(HFC), such as 1,1,1,3,3-pentafluoropropane (CHF₂CH₂CF₃, HFC-245fa,PFP), or hydrofluoroether (HFE), such as pentafluoroethyl methyl ether(CF₃CF₂OCH₃, HFE-245mc).

Among these, 1,1,1,3,3-pentafluoropropane (vapor pressure at 23° C.:0.14 MPa, boiling point: 15° C.), trichlorofluoromethane (vapor pressureat 23° C.: 0.1056 MPa, boiling point: 24° C.), and pentafluoroethylmethyl ether have good filling properties at an ambient temperature inthe range of 20° C. to 25° C. in the mold contact step. In particular,1,1,1,3,3-pentafluoropropane has improved safety.

These condensable gases may be used alone or in combination of two ormore thereof. The condensable gas may be used in combination with anoncondensable gas, such as air, nitrogen, carbon dioxide, helium,and/or argon. The noncondensable gas to be mixed with the condensablegas may be helium in terms of filling property. In this case, when therecessed portions of the micro- and/or nano-pattern on the mold 104 arefilled with the gases in the atmosphere (the condensable gas and helium)together with (part of) the coating film 106 in the mold contact step,upon liquefaction of the condensable gas, helium can pass through themold, thus improving the filling property.

<Aligning Step [3]>

As illustrated in FIG. 2C, the positions of the mold and/or theworkpiece substrate are adjusted such that a mold positioning mark 105is aligned with a workpiece substrate positioning mark 103.

<Photoirradiation Step [4]>

As illustrated in FIG. 2D, after aligning in the step [3], a contactportion between the curable composition 101 and the mold 104, morespecifically, the coating film 106 in the micro- and/or nano-pattern onthe mold 104 is irradiated with light through the mold 104 (FIG.2D(d-1)). The coating film 106 in the micro- and/or nano-pattern on themold 104 is cured by photoirradiation and forms a cured film 108 (FIG.2D(d-2)).

The type of light irradiated to the curable composition 101 of thecoating film 106 in the micro- and/or nano-pattern on the mold 104depends on the sensitive wavelength of the curable composition 101. Morespecifically, the light may be ultraviolet light having a wavelength of150 nm or more and 400 nm or less, X-rays, or an electron beam.

Among these, the light irradiated to the curable composition 101(irradiation light 107) may be ultraviolet light. This is because manycommercially available curing aids (photopolymerization initiators) aresensitive to ultraviolet light. Examples of ultraviolet light sourcesinclude, but are not limited to, high-pressure mercury lamps,ultra-high-pressure mercury lamps, low-pressure mercury lamps, deep-UVlamps, carbon are lamps, chemical lamps, metal halide lamps, xenonlamps, KrF excimer lasers, ArF excimer lasers, and F₂ excimer lasers. Inparticular, an ultra-high-pressure mercury lamp may be used as anultraviolet light source in the present embodiment. The number of lightsources to be used may be one or two or more. The coating film 106 inthe micro- and/or nano-pattern on the mold 104 may be entirely or partlyirradiated with light.

The entire substrate 102 may be intermittently or continuouslyirradiated with light. A region A may be irradiated with light in afirst irradiation process, and another region B may be irradiated withlight in a second irradiation process.

In the present embodiment, the exposure dose of the curable composition101 in the present step is preferably 90 mJ/cm² or less, more preferablya low exposure dose, most preferably 30 mJ/cm² or less. The term “a lowexposure dose”, as used herein, refers to 76 mJ/cm² or less.

In this case, a cured product of the curable composition according tothe present embodiment satisfies the following formula (1) and cansatisfy the following formula (2).

Er ₁ /Er ₂≧1.10  (1)

Er₁ denotes the surface reduced modulus (GPa) of a cured product of thecurable composition, and Er₂ denotes the internal reduced modulus (GPa)of the cured product.

Er ₃ /Er ₂≧1.40  (2)

Er₁ and Er₂ in the formula (2) are the same as Er₁ and Er₂ in theformula (1) and denote the surface reduced modulus (GPa) and theinternal reduced modulus (GPa) of the cured product, respectively.

The curable composition can also satisfy the following formula (3) aswell as the formula (1) or (2) in a cured state.

Er ₁≧3.00 GPa  (3)

The curable composition can also satisfy the formula (4) in a curedstate.

Er ₁≧3.50 GPa  (4)

Er₁ in the formulae (3) and (4) is the same as Er₁ in the formula (1) or(2) and denotes the surface reduced modulus (GPa) of the cured product.

Thus, a cured product that has a sufficiently cured surface and is lessprone to a pattern collapse defect can be formed even when the curablecomposition is cured at a low exposure dose.

<Demolding Step [5]>

The cured product 108 is then separated from the mold 104. A curedproduct 109 having a predetermined pattern is formed on the substrate102.

In the present step (demolding step), as illustrated in FIG. 2E, thecured product 108 is separated from the mold 104, and the resultingcured product 109 has a reverse pattern of the micro- and/ornano-pattern of the mold 104 formed in the step [4] (photoirradiationstep).

When the mold contact step is performed in a condensable gas atmosphere,as the pressure at the interface between the cured product 108 and themold 104 is decreased by the separation of the cured product 108 fromthe mold 104 in the demolding step, the condensable gas is vaporized andtends to effectively decrease the demolding force.

The cured product 108 may be separated from the mold 104 by any methodunder any conditions, provided that the cured product 108 is notphysically damaged. For example, the substrate 102 (workpiece substrate)may be separated from the mold 104 by fixing the substrate 102 andmoving the mold 104 away from the substrate 102, or by fixing the mold104 and moving the substrate 102 away from the mold 104, or by movingthe substrate 102 and the mold 104 in opposite directions.

A cured product having a desired uneven pattern (a pattern resultingfrom the uneven surface profile of the mold 104) at a desired positioncan be produced through the series of steps [1] to [5] (productionprocess). The cured product can also be used as an optical member, suchas a Fresnel lens or a diffraction grating (or part of an opticalmember). In such a case, the optical member can include the substrate102 and the patterned cured product 109 disposed on the substrate 102.

In a method for producing a patterned cured product according to thepresent embodiment, a repeating unit (shot) composed of the steps [1] to[5] can be performed multiple times on a single workpiece substrate. Therepeating unit (shot) composed of the steps [1] to [5] can be performedmultiple times to form a cured product having a plurality of desireduneven patterns (a pattern resulting from the uneven surface profile ofthe mold 104) at a desired position on the workpiece substrate.

<Residual Film Removal Step [6] of Removing Part of Cured Product>

Although a cured product produced in the demolding step [5] has aparticular pattern, part of the cured product may remain in a regionother than the patterned region (such part of the cured product ishereinafter also referred to as a residual film). In such a case, asillustrated in FIG. 2F, a portion of the patterned cured product in aregion to be removed (a residual film) can be removed to form a curedproduct pattern 110 having a desired uneven pattern (a pattern resultingfrom the uneven surface profile of the mold 104).

The residual film may be removed by etching a cured product (residualfilm) in the recessed portions of the cured product 109 and therebyexposing the surface of the substrate 102 in the recessed portions ofthe pattern of the cured product 109.

The cured product in the recessed portions of the cured product 109 maybe etched by any method, for example, a conventional method, such as dryetching. A known dry etching apparatus may be used in dry etching. Thesource gas for dry etching depends on the elementary composition of acured product to be etched and may be a halogen gas, such as CF₄, C₂F₆,C₃F₈, CCl₂F₂, CCl₁, CBrF₃, BCl₃, PCl₃, SF₆, or Cl₂, a gas containing anoxygen atom, such as O₂, CO, or CO₂, an inert gas, such as He, N₂, orAr, H₂, or NH₃. These gases may be used as a mixture thereof.

The cured product pattern 110 having a desired uneven pattern (a patternresulting from the uneven surface profile of the mold 104) at a desiredposition can be produced through the production process including thesteps [1] to [6]. An article having the cured product pattern can alsobe produced. When the substrate 102 is processed utilizing the curedproduct pattern 110, a substrate processing step (step [7]) is performedas described below.

The cured product pattern 110 can be used as an optical member, such asa diffraction grating or polarizer, (or part of an optical member) toproduce an optical component. In such a case, the optical component caninclude the substrate 102 and the cured product pattern 110 disposed onthe substrate 102.

<Substrate Processing Step [7]>

The cured product pattern 110 having an uneven pattern produced by amethod for producing a patterned cured product according to the presentembodiment can be used as a film for use in interlayer insulating filmsof electronic components exemplified by semiconductor devices, such asLSI, system LSI, DRAM, SDRAM, RDRAM, and D-RDRAM, and can also be usedas a resist film in the manufacture of semiconductor devices.

When the cured product pattern 110 is used as a resist film, an exposedsurface of the substrate in the etching step [6] (a region 111 in FIG.2F) is subjected to etching or ion implantation. The cured productpattern 110 functions as an etching mask. Furthermore, a circuitstructure 112 based on the pattern of the cured product pattern 110(FIG. 2G) can be formed on the substrate 102 by forming an electroniccomponent. Thus, a circuit board for use in semiconductor devices can bemanufactured. This circuit board can be coupled to a circuit controlmechanism for the circuit board to form electronic equipment, such asdisplays, cameras, and medical devices.

Likewise, an optical component can be manufactured by etching or ionimplantation using the cured product pattern 110 as a resist film.

In the manufacture of circuitized substrates and electronic components,the cured product pattern 110 may be finally removed from the processedsubstrate or may be left as a member of the device.

EXEMPLARY EMBODIMENTS

The present invention will be further described with the followingexemplary embodiments. However, the technical scope of the presentinvention is not limited to these exemplary embodiments.

Comparative Example 1

(1) Preparation of Curable Composition (b-1)

A blend of the following components (A) and (B) was passed through a 0.2μm ultra-high molecular weight polyethylene filter to prepare a curablecomposition (b-1) according to Comparative Example 1.

(1-1) Component (A): 94 parts by weight in total

<A-1> Isobornyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd.,trade name: IB-XA): 9.0 parts by weight

<A-2> Benzyl acrylate (manufactured by Osaka Organic Chemical IndustryLtd., trade name: V#160): 38.0 parts by weight

<A-3> Neopentyl glycol diacrylate (manufactured by Kyoeisha ChemicalCo., Ltd., trade name: NP-A): 47.0 parts by weight

(1-2) Component (B): 3 parts by weight in total

<B-1> Irgacure 651 (manufactured by BASF): 3 parts by weight

(2) Preparation of Cured Product of Curable Composition

2 μL of the curable composition (b-1) was dropped on a silicon wafer onwhich an adhesion-promoting layer having a thickness of 60 nm was formedas an adhesion layer. The silicon wafer was covered with a quartz glasssheet having a thickness of 1 mm, thereby filling a 25 mm×25 mm regionwith the curable composition (b-1).

The coating film was then irradiated for 200 seconds with lightirradiated from a UV light source equipped with an ultra-high-pressuremercury lamp through an interference filter described below and throughthe quartz glass sheet. The interference filter used for thephotoirradiation was VPF-25C-10-15-31300 (manufactured by Sigmakoki Co.,Ltd.). The irradiation light was single-wavelength ultraviolet lighthaving a wavelength in the range of 308 to 318 nm. The illuminance was 1mW/cm².

After the photoirradiation, the quartz glass sheet was removed. A curedproduct (b-1-200) of the curable composition (b-1) cured at an exposuredose of 200 mJ/cm² was formed on the silicon wafer. The cured product(b-1-200) had an average film thickness of 3.2 m.

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (b-1-200) was measured with ananoindenter apparatus (TI-950 TriboIndenter, manufactured by HysitronCorporation) 24 hours after curing. In the present specification, thereduced modulus was measured with the nanoindenter apparatus equippedwith a diamond indenter (TI-0037, 90-degree cube corner type,manufactured by Hysitron Corporation), which was calibrated using fusedquartz as a standard sample.

The surface reduced modulus Er₁ (GPa) of the cured product wasdetermined by measuring the load (P) and displacement (indentation depthh) while the surface was indented with the diamond indenter to anindentation depth of approximately 10 nm, determining the slopeP^(2/3)/h in a region in which a “P^(2/3) vs. h” line was substantiallystraight (immediately after loading, at an indentation depth in therange of 0 to 4 nm) by the Hertz method, substituting the slopeP^(2/3)/h into the following mathematical formula (1) to determine anaverage reduced modulus in a depth range of 4 nm or less from thesurface of the cured product, and averaging average reduced modulimeasured in this manner at 15 points. In the mathematical formula (1), Rdenotes the tip radius of the indenter used for the measurement. Theindenter tip radius R was determined using this formula fromnanoindentation of fused quartz with the used indenter.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 3} \right\rbrack & \; \\{{Er}_{1} = {\frac{3}{4}\left( {\frac{1}{R^{1/2}}\frac{P}{h^{3/2}}} \right)}} & {{Formula}\mspace{14mu} (1)}\end{matrix}$

The internal reduced modulus Er₂ (GPa) of the cured product wasdetermined by measuring the load (P) and displacement (indentation depthh) while the surface of the cured product was indented with the diamondindenter to an indentation depth of 200 nm, substituting the slope S ofa tangent line of the “P vs. h” curve immediately after unloading intothe following mathematical formula (2) by the Oliver-Pharr method todetermine the reduced modulus at a depth of 200 nm from the surface ofthe cured product, and averaging reduced moduli measured in this mannerat 15 points. In the mathematical formula (2), A_(c) denotes the contactprojected area, which depends on the indenter used for the measurementand the indentation depth. The contact projected area A_(c) wasdetermined from a calibration curve (the relationship between theindentation depth and the contact projected area of the used indenter)obtained using this formula from nanoindentation of fused quartz withthe used indenter.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 4} \right\rbrack & \; \\{{Er}_{2} = \frac{S\sqrt{\pi}}{2\sqrt{A_{c}}}} & {{Formula}\mspace{14mu} (2)}\end{matrix}$

The surface reduced modulus Er₁ of the cured product (b-1-200) was 3.39GPa. The internal reduced modulus Er₂ of the cured product (b-1-200) was3.21 GPa. Er₁/Er₂ was 1.06.

(4) Observation of Nanoimprint Pattern

A nanoimprint pattern of the curable composition (b-1) was formed by thefollowing method and was observed with an electron microscope.

(4-1) Placement Step

1440 droplets (11 pL/droplet) of the curable composition (b-1) weredropped by an ink jet method on a 300-mm silicon wafer on which anadhesion-promoting layer having a thickness of 3 nm was formed as anadhesion layer. These droplets were disposed at substantially regularintervals in a region 26 mm in length and 33 mm in width.

(4-2) Mold Contact Step and Photoirradiation Step

A 28-nm line and space (L/S) pattern having a height of 60 nm was formedon the curable composition (b-1) on the silicon wafer and was broughtinto contact with a quartz mold (26 mm in length and 33 mm in width) notsubjected to surface treatment.

30 seconds after the contact with the quartz mold, the curablecomposition (b-1) was irradiated with UV light emitted from a UV lightsource equipped with a 200-W mercury-xenon lamp (EXECURE 3000,manufactured by HOYA CANDEO OPTRONICS CORPORATION) through the quartzmold. During the UV light irradiation, an interference filter that canselectively transmit light having a wavelength in the range of 308 to318 nm (VPF-50C-10-25-31300, manufactured by Sigmakoki Co., Ltd.) wasplaced between the UV light source and the quartz mold. The illuminanceof the UV light directly under the quartz mold was 40 mW/cm² at awavelength of 313 nm. UV light irradiation under such conditions wasperformed for 0.25 to 5.00 seconds (exposure dose: 10 to 189 mJ/cm²).

(4-3) Demolding Step

The quartz mold was raised at 0.5 mm/s to separate the mold from thecured product.

(4-4) Observation of Nanoimprint Pattern with Electron Microscope

Observation of a 6.75 μm×6.75 μm area of a nanoimprint pattern with anelectron microscope showed that there was a defect, such as patterncollapse, at a low exposure dose of 76 mJ/cm² or less.

The minimum exposure dose required for the curable composition (b-1) toform a satisfactory pattern free of pattern collapse and other defectswas 90 mJ/cm² or more.

The pattern collapse means that at least part of adjacent lines of the28-nm line and space (L/S) pattern having a height of 60 nm are incontact.

Exemplary Embodiment 1

(1) Preparation of Curable Composition (a-1)

A curable composition (a-1) was prepared in the same manner as inComparative Example 1 except that 1.1 parts by weight of <C-1> TF-2067(manufactured by DIC Corporation) represented by the following formula(c) was used as an additive component (C) in addition to the components(A) and (B).

(2) Preparation of Cured Product of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-1) having a thickness of 3.2 μm on a silicon wafer wascured at an exposure dose of 200 mJ/cm² to form a cured product(a-1-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-1-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-1-200) were4.33 and 2.87 GPa, respectively, and Er₁/Er₂ was 1.51.

(4) Observation of Nanoimprint Pattern

A nanoimprint pattern of the curable composition (a-1) was formed in thesame manner as in Comparative Example 1 and was observed with anelectron microscope. The observation showed that a satisfactory patternfree of pattern collapse and other defects was formed even at a lowexposure dose in the range of 19 to 76 mJ/cm².

Exemplary Embodiment 2

(1) Preparation of Curable Composition (a-2)

A curable composition (a-2) was prepared in the same manner as inComparative Example 1 except that 0.9 parts by weight of <C-2> SR-715(manufactured by Aoki Oil Industrial Co., Ltd.) represented by thefollowing formula (d) was used as an additive component (C) in additionto the components (A) and (B).

(2) Preparation of Cured Product of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-2) having a thickness of 3.2 μm on a silicon wafer wascured at an exposure dose of 200 mJ/cm² to form a cured product(a-2-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-2-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-2-200) were5.10 and 2.90 GPa, respectively, and Er₁/Er₂ was 1.76.

(4) Observation of Nanoimprint Pattern

A nanoimprint pattern of the curable composition (a-2) was formed in thesame manner as in Comparative Example 1 and was observed with anelectron microscope. The observation showed that a satisfactory patternfree of pattern collapse and other defects was formed even at a lowexposure dose in the range of 10 to 76 mJ/cm².

Comparative Example 2

(1) Preparation of Curable Composition (b-2)

A curable composition (b-2) was prepared in the same manner as inComparative Example 1 except that 0.8 parts by weight of <C-3> PluriolA760E (manufactured by BASF) represented by the following formula (e)was used as an additive component (C) in addition to the components (A)and (B).

(2) Preparation of Cured Product of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (b-2) having a thickness of 3.2 μm on a silicon wafer wascured at an exposure dose of 200 mJ/cm² to form a cured product(b-2-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (b-2-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (b-2-200) were2.90 and 3.04 GPa, respectively, and Er₁/Er₂ was 0.953.

(4) Observation of Nanoimprint Pattern

A nanoimprint pattern of the curable composition (b-2) was formed in thesame manner as in Comparative Example 1 and was observed with anelectron microscope. The observation showed that there was a defect,such as pattern collapse, at a low exposure dose of 76 mJ/cm² or less.

The minimum exposure dose required for the curable composition (b-2) toform a satisfactory pattern free of pattern collapse and other defectswas 90 mJ/cm² or more.

Exemplary Embodiment 3

(1) Preparation of Curable Composition (a-3)

A curable composition (a-3) was prepared in the same manner as inComparative Example 1 except that the component (B) was 3 parts byweight of <B-2> Irgacure 369 (manufactured by BASF) represented by thefollowing formula (b).

(2) Preparation of Cured Product of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-3) having a thickness of 3.2 μm on a silicon wafer wascured at an exposure dose of 200 mJ/cm² to form a cured product(a-3-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-3-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-3-200) were5.75 and 3.51 GPa, respectively, and Er₁/Er₂ was 1.64.

(4) Observation of Nanoimprint Pattern

A nanoimprint pattern of the curable composition (a-3) was formed in thesame manner as in Comparative Example 1 and was observed with anelectron microscope. The observation showed that a satisfactory patternfree of pattern collapse and other defects was formed even at a lowexposure dose in the range of 10 to 76 mJ/cm².

Exemplary Embodiment 4

(1) Preparation of Curable Composition (a-4)

A blend of the following component (A), component (B), and additivecomponent (C) was passed through a 0.2 μm ultra-high molecular weightpolyethylene filter to prepare a curable composition (a-4).

(1-1) Component (A): 100 parts by weight in total

<A-2> Benzyl acrylate (manufactured by Osaka Organic Chemical IndustryLtd., trade name: V#160): 50 parts by weight

<A-4> m-xylylene diacrylate: 50 parts by weight

(1-2) Component (B): 3 parts by weight in total

<B-3> Lucirin TPO (manufactured by BASF): 3 parts by weight

(1-3) Additive component (C) other than components (A) and (B): 1.3parts by weight in total

<C-4> Polyoxyethylene stearyl ether Emulgen 320P (manufactured by KaoCorporation): 0.8 parts by weight

<C-5> 4,4′-bis(diethylamino)benzophenone (manufactured by Tokyo ChemicalIndustry Co., Ltd.): 0.5 parts by weight

(2) Preparation of Cured Product of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-4) having a thickness of 3.2 m on a silicon wafer wascured at an exposure dose of 200 mJ/cm² to form a cured product(a-4-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-4-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-4-200) were5.90 and 4.04 GPa, respectively, and Er₁/Er₂ was 1.46.

(4) Observation of Nanoimprint Pattern

It is assumed from the measurement of the reduced modulus of the curedproduct (a-4-200) that a satisfactory nanoimprint pattern of the curablecomposition (a-4) free of pattern collapse and other defects can beformed in the same manner as in Comparative Example 1 even at a lowexposure dose in the range of 10 to 76 mJ/cm².

Exemplary Embodiment 5

(1) Preparation of Curable Composition (a-5)

A curable composition (a-5) was prepared in the same manner as inExemplary Embodiment 4 except that the component (A) was composed of 45parts by weight of <A-2> benzyl acrylate (manufactured by Osaka OrganicChemical Industry Ltd., trade name: V#160), 50 parts by weight of <A-4>m-xylylene diacrylate, and 5 parts by weight of <A-5> 2-naphthylmethylacrylate.

(2) Preparation of Cured Film of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-5) having a thickness of 3.2 μm on a silicon wafer wasexposed to light at 200 mJ/cm² to form a cured film (a-5-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-5-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-5-200) were6.02 and 4.00 GPa, respectively, and Er₁/Er₂ was 1.51.

(4) Observation of Nanoimprint Pattern

It is assumed from the measurement of the reduced modulus of the curedproduct (a-5-200) that a satisfactory nanoimprint pattern of the curablecomposition (a-5) free of pattern collapse and other defects can beformed in the same manner as in Comparative Example 1 even at a lowexposure dose in the range of 10 to 76 mJ/cm².

Exemplary Embodiment 6

(1) Preparation of Curable Composition (a-6)

A curable composition (a-6) was prepared in the same manner as inExemplary Embodiment 4 except that the component (A) was composed of 50parts by weight of <A-2> benzyl acrylate (manufactured by Osaka OrganicChemical Industry Ltd., trade name: V#160) and 50 parts by weight of<A-7> phenylethylene glycol diacrylate.

(2) Preparation of Cured Film of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-6) having a thickness of 3.2 μm on a silicon wafer wasexposed to light at 200 mJ/cm² to form a cured film (a-6-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-6-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-6-200) were4.20 and 3.76 GPa, respectively, and Er₁/Er₂ was 1.12.

(4) Observation of Nanoimprint Pattern

It is assumed from the measurement of the reduced modulus of the curedproduct (a-6-200) that a satisfactory nanoimprint pattern of the curablecomposition (a-6) free of pattern collapse and other defects can beformed in the same manner as in Comparative Example 1 even at a lowexposure dose in the range of 10 to 76 mJ/cm².

Exemplary Embodiment 7

(1) Preparation of Curable Composition (a-7)

A curable composition (a-7) was prepared in the same manner as inExemplary Embodiment 6 except that the additive component (C) wascomposed of 1.6 parts by weight of <C-6> polyoxyethylene stearyl etherSR-730 (manufactured by Aoki Oil Industrial Co., Ltd.) and 0.5 parts byweight of <C-5>4,4′-bis(diethylamino)benzophenone (manufactured by TokyoChemical Industry Co., Ltd.).

(2) Preparation of Cured Film of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-7) having a thickness of 3.2 m on a silicon wafer wasexposed to light at 200 mJ/cm² to form a cured film (a-7-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-7-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-7-200) were4.60 and 3.84 GPa, respectively, and Er₁/Er₂ was 1.20.

(4) Observation of Nanoimprint Pattern

It is assumed from the measurement of the reduced modulus of the curedproduct (a-7-200) that a satisfactory nanoimprint pattern of the curablecomposition (a-7) free of pattern collapse and other defects can beformed in the same manner as in Comparative Example 1 even at a lowexposure dose in the range of 10 to 76 mJ/cm².

Comparative Example 3

(1) Preparation of Curable Composition (b-3)

A blend of the following components (A) and (B) was passed through a 0.2μm ultra-high molecular weight polyethylene filter to prepare a curablecomposition (b-3).

(1-1) Component (A): 100 parts by weight in total

<A-2> Benzyl acrylate (manufactured by Osaka Organic Chemical IndustryLtd., trade name: V#160): 50 parts by weight

<A-7> Phenylethylene glycol diacrylate: 50 parts by weight

(1-2) Component (B): 3 parts by weight in total

<B-3> Lucirin TPO (manufactured by BASF): 3 parts by weight

(2) Preparation of Cured Product of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (b-3) having a thickness of 3.2 μm on a silicon wafer wascured at an exposure dose of 200 mJ/cm² to form a cured product(b-3-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (b-3-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (b-3-200) were3.54 and 3.87 GPa, respectively, and Er₁/Er₂ was 0.915.

(4) Observation of Nanoimprint Pattern

It is assumed from the measurement of the reduced modulus of the curedproduct (b-3-200) that a nanoimprint pattern of the curable composition(b-3) formed in the same manner as in Comparative Example 1 will have adefect, such as pattern collapse, at a low exposure dose of 76 mJ/cm² orless.

Exemplary Embodiment 8

(1) Preparation of Curable Composition (a-8)

A curable composition (a-8) was prepared in the same manner as inComparative Example 1 except that the component (B) was 3 parts byweight of <B-3> Lucirin TPO (manufactured by BASF) represented by thefollowing formula (f).

(2) Preparation of Cured Product of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-8) having a thickness of 3.2 μm on a silicon wafer wascured at an exposure dose of 200 mJ/cm² to form a cured product(a-8-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-8-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-8-200) were5.12 and 3.64 GPa, respectively, and Er₁/Er₂ was 1.41.

(4) Observation of Nanoimprint Pattern

It is assumed from the measurement of the reduced modulus of the curedproduct (a-8-200) that a satisfactory nanoimprint pattern of the curablecomposition (a-8) free of pattern collapse and other defects can beformed in the same manner as in Comparative Example 1 even at a lowexposure dose in the range of 10 to 76 mJ/cm².

Exemplary Embodiment 9

(1) Preparation of Curable Composition (a-9)

A blend of the following components (A) and (B) was passed through a 0.2μm ultra-high molecular weight polyethylene filter to prepare a curablecomposition (a-9).

(1-1) Component (A): 100 parts by weight in total

<A-8> Dicyclopentanyl acrylate (manufactured by Hitachi Chemical Co.,Ltd., trade name: FA-513AS): 50 parts by weight

<A-4> m-xylylene diacrylate: 50 parts by weight

(1-2) Component (B): 3 parts by weight in total

<B-2> Irgacure 369 (manufactured by BASF): 3 parts by weight

(2) Preparation of Cured Product of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-9) having a thickness of 3.2 m on a silicon wafer wascured at an exposure dose of 200 mJ/cm² to form a cured product(a-9-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-9-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-9-200) were5.57 and 3.47 GPa, respectively, and Er₁/Er₂ was 1.61.

(4) Observation of Nanoimprint Pattern

It is assumed from the measurement of the reduced modulus of the curedproduct (a-9-200) that a satisfactory nanoimprint pattern of the curablecomposition (a-9) free of pattern collapse and other defects can beformed in the same manner as in Comparative Example 1 even at a lowexposure dose in the range of 10 to 76 mJ/cm².

Exemplary Embodiment 10

(1) Preparation of Curable Composition (a-10)

A blend of the following component (A), component (B), and additivecomponent (C) was passed through a 0.2 μm ultra-high molecular weightpolyethylene filter to prepare a curable composition (a-10).

(1-1) Component (A): 100 parts by weight in total

<A-1> Isobornyl acrylate (manufactured by Kyoeisha Chemical Co., td.,trade name: IB-XA): 75 parts by weight

<A-9> 1,10-decanediol diacrylate (manufactured by Shin Nakamura ChemicalCo., Ltd., trade name: A-DOD-N): 25 parts by weight

(1-2) Component (B): 3 parts by weight in total

<B-3> Lucirin TPO (manufactured by BASF): 3 parts by weight

(1-3) Additive component (C) other than components (A) and (B): 0.5parts by weight in total

<C-5> 4,4′-bis(diethylamino)benzophenone (manufactured by Tokyo ChemicalIndustry Co., Ltd.): 0.5 parts by weight

(2) Preparation of Cured Product of Curable Composition

In the same manner as in Comparative Example 1, a film of the curablecomposition (a-10) having a thickness of 3.2 μm on a silicon wafer wascured at an exposure dose of 200 mJ/cm² to form a cured product(a-10-200).

(3) Measurement of Reduced Modulus of Cured Product

The reduced modulus of the cured product (a-10-200) was measured in thesame manner as in Comparative Example 1. The surface reduced modulus Er₁and the internal reduced modulus Er₂ of the cured product (a-10-200)were 3.51 and 2.73 GPa, respectively, and Er₁/Er₂ was 1.29.

(4) Observation of Nanoimprint Pattern

It is assumed from the measurement of the reduced modulus of the curedproduct (a-10-200) that a satisfactory nanoimprint pattern of thecurable composition (a-10) free of pattern collapse and other defectscan be formed in the same manner as in Comparative Example 1 even at alow exposure dose in the range of 10 to 76 mJ/cm².

Tables 1, 2, and 3 summarize the results of the exemplary embodimentsand comparative examples.

TABLE 1 Pattern collapse evaluation results for low exposure dose (76mJ/cm² or less) and surface and internal reduced moduli and ratiothereof of cured product cured at exposure dose in early stage ofreduced modulus saturation (200 mJ/cm²) Curable Exposure dose (mJ/cm²)Er₁ Er₂ composition 10 19 29 38 57 76 (GPa) (GPa) Er₁/Er₂ Exemplary a-1X ◯ ◯ ◯ ◯ ◯ 4.33 2.87 1.51 embodiment 1 Exemplary a-2 ◯ ◯ ◯ ◯ ◯ ◯ 5.102.90 1.76 embodiment 2 Exemplary a-3 ◯ ◯ ◯ ◯ ◯ ◯ 5.75 3.51 1.64embodiment 3 Comparative b-1 X X X X X X 3.39 3.21 1.06 example 1Comparative b-2 X X X X X X 2.90 3.04 0.953 example 2 Symbol ◯: Asatisfactory pattern free of pattern collapse and other defects SymbolX: A pattern having a defect, such as pattern collapse Er₁: Surfacereduced modulus of a cured product Er₂: Internal reduced modulus of acured product

Exposure dose in an early stage of reduced modulus saturation: Exposuredose in an early stage in which the reduced modulus is substantiallyconstant as a result of progress in curing

First examined is the relationship between the pattern collapseevaluation result for the low exposure dose (76 mJ/cm² or less) and thecurable composition. A comparison of Exemplary Embodiments 1 and 2 withComparative Examples 1 and 2 shows that the evaluation results ofpattern collapse at the low exposure dose depend significantly on theaddition and type of the surfactant component (C). A comparison ofExemplary Embodiment 3 with Comparative Example 1 showed that theevaluation results of pattern collapse at the low exposure dose alsodepend significantly on the type of the photopolymerization initiatorcomponent (B).

The measurement results of the surface and internal reduced moduli ofthe cured product show that the internal reduced modulus Er₂ of thecured product in Exemplary Embodiments 1 to 3 is lower than that ofComparative Examples 1 and 2. However, pattern collapse at the lowexposure dose (76 mJ/cm² or less) is suppressed in Exemplary Embodiments1 to 3. The ratio Er₁/Er₂ of the surface reduced modulus Er₁ to theinternal reduced modulus Er₂ of the cured product in ExemplaryEmbodiments 1 to 3 is greater than that in Comparative Examples 1 and 2.This means that a hard layer is formed on the surface of the curedproduct.

The ratio Er₁/Er₂ of the surface reduced modulus Er₁ to the internalreduced modulus Er₂ of the cured product cured at an exposure dose inthe early stage of reduced modulus saturation (200 mJ/cm²) tends to bemaintained even when the curable composition is cured at the lowexposure dose.

Thus, the curable compositions having Er₁/Er₂≧1.10 according toExemplary Embodiments 1 to 3 are curable compositions for nanoimprintingthat can form a cured product that has a sufficiently cured surface andis less prone to a pattern collapse defect even when the curablecompositions are cured by a photo-nanoimprint method at the low exposuredose.

TABLE 2 Surface and internal reduced moduli and ratio thereof of curedproduct cured at exposure dose in early stage of reduced modulussaturation (200 mJ/cm²) Curable composition Er₁ (GPa) Er₂ (GPa) Er₁/Er₂Exemplary a-4 5.90 4.04 1.46 embodiment 4 Exemplary a-5 6.02 4.00 1.51embodiment 5 Exemplary a-6 4.20 3.76 1.12 embodiment 6 Exemplary a-74.60 3.84 1.20 embodiment 7 Exemplary a-8 5.12 3.64 1.41 embodiment 8Comparative b-3 3.54 3.87 0.915 example 3 Er₁: Surface reduced modulusof a cured product Er₂: Internal reduced modulus of a cured product

Exposure dose in an early stage of reduced modulus saturation: Exposuredose in an early stage in which the reduced modulus is substantiallyconstant as a result of progress in curing

TABLE 3 Surface and internal reduced moduli and ratio thereof of curedproduct cured at exposure dose in early stage of reduced modulussaturation (200 mJ/cm²) Curable composition Er₁ (GPa) Er₂ (GPa) Er₁/Er₂Exemplary a-9 5.57 3.47 1.61 embodiment 9 Exemplary a-10 3.51 2.73 1.29embodiment 10 Er₁: Surface reduced modulus of a cured product Er₂:Internal reduced modulus of a cured product

Exposure dose in an early stage of reduced modulus saturation: Exposuredose in an early stage in which the reduced modulus is substantiallyconstant as a result of progress in curing

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2014-097768, filed May 9, 2014, No. 2014-151501, filed Jul. 25, 2014,and No. 2014-257799, filed Dec. 19, 2014, which are hereby incorporatedby reference herein in their entirety.

INDUSTRIAL APPLICABILITY

As described above, the present invention provides a photocurablecomposition for nanoimprinting that can form a cured product that has asufficiently cured surface and is less prone to a pattern collapsedefect even when the photocurable composition is cured at a low exposuredose. The present invention also provides a nanoimprint method forforming such a cured product. A method for producing a film according tothe present invention can be utilized to manufacture cured products,optical components, circuit boards, electronic components, andelectronic equipment.

1. A curable composition that satisfies the following formula (1) in acured state:Er ₁ /Er ₂≧1.10  (1) wherein Er₁ denotes a surface reduced modulus (GPa)of a cured product of the curable composition, and Er₂ denotes aninternal reduced modulus (GPa) of the cured product.
 2. The curablecomposition according to claim 1, comprising: a polymerizable compoundcomponent (A); and a photopolymerization initiator component (B),wherein the cured state is a cured product of the curable compositioncured at an exposure dose of 200 mJ/cm² has an average film thickness of3.2 μm: wherein Er₁ denotes an average reduced modulus (GPa) in a depthrange of 4 nm or less from a surface of the cured product, and Er₂denotes a reduced modulus (GPa) at a depth of 200 nm from the surface ofthe cured product.
 3. The curable composition according to claim 1,wherein Er₁ is an average surface reduced modulus (GPa) of the curedproduct measured with a nanoindenter and determined by a Hertz method,and Er₂ is an internal reduced modulus (GPa) of the cured productmeasured with a nanoindenter and determined by an Oliver-Pharr method.4. The curable composition according to claim 1, further satisfying thefollowing formula (3):Er ₁≧3.00  (3) wherein Er₁ denotes a surface reduced modulus (GPa) ofthe cured product.
 5. The curable composition according to claim 1,wherein the component (A) is composed mainly of a monofunctional(meth)acrylic compound and/or a polyfunctional (meth)acrylic compound.6. The curable composition according to claim 1, wherein the component(A) contains at least one of isobornyl acrylate, benzyl acrylate,2-naphthylmethyl acrylate, dicyclopentanyl acrylate, m-xylylenediacrylate, dimethyloltricyclodecane diacrylate, phenylethylene glycoldiacrylate, 1,10-decanediol diacrylate, and neopentyl glycol diacrylate.7. The curable composition according to claim 1, wherein the component(A) is composed mainly of a (meth)acrylic compound, and 20% by weight ormore of the component (A) is a polyfunctional (meth)acrylic compound. 8.The curable composition according to claim 1, wherein the component (A)is composed mainly of a (meth)acrylic compound, and 30% by weight ormore of the component (A) is a (meth)acrylic compound having a ringstructure.
 9. The curable composition according to claim 1, wherein thecomponent (A) is composed mainly of dicyclopentanyl acrylate andm-xylylene diacrylate, and the weight ratio of dicyclopentanyl acrylateto m-xylylene diacrylate ranges from 40:60 to 60:40.
 10. The curablecomposition according to claim 1, wherein the component (B) contains atleast one of alkylphenone polymerization initiators and acylphosphineoxide polymerization initiators.
 11. The curable composition accordingto claim 1, wherein the component (B) contains at least one of2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 and2,4,6-trimethylbenzoyldiphenylphosphine oxide.
 12. The curablecomposition according to claim 1, wherein the component (A) is composedmainly of dicyclopentanyl acrylate and m-xylylene diacrylate, the weightratio of dicyclopentanyl acrylate to m-xylylene diacrylate ranges from40:60 to 60:40, and the amount of component (B) ranges from 0.01% to 10%by weight of the total amount of the component (A).
 13. The curablecomposition according to claim 1, further comprising at least one offluorosurfactants and hydrocarbon surfactants as an internal releaseagent.
 14. The curable composition according to claim 1, furthercomprising at least one sensitizer having a benzophenone structure. 15.The curable composition according to claim 1, further comprising atleast one hydrogen donor having a benzophenone structure.
 16. Thecurable composition according to claim 1, wherein the curablecomposition has a viscosity of 1 cP or more and 100 cP or less.
 17. Thecurable composition according to claim 1, wherein the curablecomposition is a composition for photo-nanoimprinting.
 18. A curedproduct of the curable composition according to claim
 1. 19. A methodfor producing a patterned film, comprising: a step [1] of placing thecurable composition according to claim 1 on a substrate; a step [2] ofbringing the curable composition into contact with a mold having anoriginal pattern to be transferred; a step [3] of aligning the substratewith the mold; a step [4] of forming a cured film by photoirradiation ofthe curable composition; and a step [5] of separating the cured filmfrom the mold.
 20. The method for producing a patterned film accordingto claim 19, wherein the mold in the step of bringing the curablecomposition into contact with a mold having an original pattern to betransferred has a pattern height of 4 nm or more and 200 nm or less andan aspect ratio of 1 or more and 10 or less.
 21. The method forproducing a patterned film according to claim 19, wherein the exposuredose in the step of forming a cured film by photoirradiation of thecurable composition is 90 mJ/cm² or less.
 22. The method for producing afilm according to claim 19, wherein the mold contact step is performedin an atmosphere containing a condensable gas.
 23. The method forproducing a film according to claim 22, wherein the condensable gas is1,1,1,3,3-pentafluoropropane.
 24. The method for producing a filmaccording to claim 22, wherein the atmosphere containing a condensablegas is a gas mixture of helium and the condensable gas.
 25. A method formanufacturing an optical component, comprising a step of forming apatterned film by the method for producing a film according to claim 19.26. A method for manufacturing a circuit board, comprising: a step offorming a patterned film by the method for producing a film according toclaim 19; and a step of subjecting the substrate to etching or ionimplantation using the patterned film as a mask.
 27. The method formanufacturing a circuit board according to claim 26, wherein the circuitboard is a semiconductor device.
 28. A method for manufacturing anelectronic component, comprising a step of forming a patterned film bythe method for producing a film according to claim
 19. 29. A curablecomposition, comprising: a polymerizable compound component (A); and aphotopolymerization initiator component (B), wherein the curablecomposition satisfies the following formula (1) when a cured product ofthe curable composition cured at an exposure dose of 200 mJ/cm² has anaverage film thickness of 3.2 μm:Er ₁ /Er ₂≧1.10  (1) wherein Er₁ denotes an average reduced modulus(GPa) in a depth range of 4 nm or less from a surface of the curedproduct, and Er₂ denotes a reduced modulus (GPa) at a depth of 200 nmfrom the surface of the cured product.